Many computer input and control systems are being developed which respond to hand motions and gestures. Rather than typing, pressing buttons, or operating a cursor control device, the user makes hand motions in front of a camera. Simpler systems respond only to hand waves and arm motions. For more detailed control, the movements of individual fingers are tracked.
In some systems, a depth-based hand tracking system is used. A camera system with multiple sensors determines, not only the appearance of the hand, but also the distance to different points on the hand. The output of a hand tracking system is a full hand skeleton. The system tracks not only the movements of finger tips, but also the individual finger joints and wrist, the angles between the bones and the global position of the hand in space. Some systems track hand movements in three dimensions by fitting a model of the hand to an input video of the hand from the system camera.
Once the hand motion is determined, then the motion can be interpreted as an input, such as a command, to the computing system. The hand tracking system delivers a command to an input system which then executes the command. Hand tracking can also be used for authentication and other purposes.